Health care professionals should be knowledgeable about the signs of congenital glaucoma. Unlike most adult forms, pediatric glaucoma is not a “silent” disease, because the elasticity of the infant eye allows for stretching of ocular tissues up to 3 years of age. This causes a variety of signs and symptoms, including epiphora (tearing), photophobia (light sensitivity), a cloudy or hazy cornea, and buphthalmos (ocular enlargement). Even something as subtle as a 4-month-old's not smiling back at his or her parent may be the first sign that something is wrong with the baby's visual system. An observation of this missed developmental milestone may prompt a parent to bring the child in for an evaluation, and glaucoma may be the culprit.
The management of pediatric glaucoma still relies heavily on angle surgery to cleave open a maldeveloped angle. Expert gonioscopic skills are essential to recognize and treat congenital glaucoma (Figure 1).1 The big development in pediatric angle surgery over the past 3 decades is circumferential canal surgery, the ability to open the canal for 360º at one sitting in a highly reliable and accurate way with either a suture or a microcatheter (iTrack; iScience Interventional). The ophthalmologist's ability to visualize the position of the normally hidden canal probe through the tissues via the illuminated iTrack is a major advance in canal surgery and in teaching angle surgery. Another significant step forward is the use of drainage implants when angle surgery is unsuccessful or contraindicated. In years past, cyclocryosurgery was the mainstay when trabeculotomy and trabeculectomy failed. Today, glaucoma subspecialists such as myself increase aqueous outflow by implanting drainage devices instead of destroying the ciliary body through the application of cryosurgery. The days of cyclocryosurgery with phthisis bulbi are no more. If cyclodestruction becomes necessary, a kinder, gentler transscleral or endoscopic cyclodiode laser (Endo Optiks) works quite well.
IMPORTANCE OF AGE OF ONSET
The reader should be aware that the age of onset of congenital glaucoma is one of the most important factors that influence the surgical outcome and, therefore, the patient's visual potential. Although it is difficult to classify the childhood glaucomas (see Classification of Primary Childhood Glaucomas), the attempt helps surgeons to formulate a treatment plan and prognosis. This article excludes secondary pediatric glaucomas (eg, trauma, retinoblastoma, uveitis, medulloepithelioma), because they are far too complex for this discussion.
HISTOPATHOLOGIC SEVERITY OF OUTFLOW AND GONIODYSGENESIS
Alvarado and colleagues correlated the histopathologic appearance of the outflow system with goniodysgenesis.2 Severely compromised aqueous outflow at birth causes a marked elevation in IOP and a cloudy cornea that may result in Haab striae (Figure 2). A diagnosis of glaucoma within the first month of life signifies a guarded prognosis. The disease results from a highly maldeveloped outflow system (severe goniodysgenesis, type 1; see Table). These patients have only a rudimentary venous channel system and therefore require an artificial drainage system such as a drainage implant or filter. Infants with mildly compromised outflow channels will demonstrate signs and symptoms of congenital glaucoma several months after birth. These patients have a much better surgical prognosis, because their canal system has developed enough to allow for surgical cleavage. In contrast, in phenotype 1, the outflow channels have not formed enough for surgical correction.
If possible, especially in infants, I avoid trabeculectomy because it will require a lifetime of vigilance for blebitis, bleb dysesthesia, hypotony, and endophthalmitis.
SURGERY FOR PEDIATRIC GLAUCOMAS
The majority of pediatric glaucomas are due to abnormal development of the chamber angle with incomplete cleavage of the outflow structures associated with iridotrabeculodysgenesis. Types 2 and 3 dysgenesis may respond quite nicely to a trabeculotomy, a procedure designed to interiorize a maldeveloped canal system. Trabeculotomy has evolved from cleaving Schlemm canal with a metal trabeculotome to 360º trabeculotomy with a Prolene suture (Ethicon, Inc.)3 to circumferential cleavage with an illuminated microcatheter (Figure 3 and see Take the Congenital Glaucoma Quiz).4,5 If the microcatheter comes out of the canal and courses over the suprachoroidal space, it readily becomes visible beneath the sclera. It is impossible to perform trabeculotomy procedures successfully in infants with type 1 goniodysgenesis, because they do not have a canal system. These patients benefit from drainage device surgery.
Goniotomy and metal trabeculotome trabeculotomy produce similar results, and the former remains a staple for many surgeons. I prefer 360º trabeculotomy,6 because the entire angle is opened at one sitting, circumferential return of the probe confirms the correct location of the canal, a cloudy cornea is not an impediment, and recent studies point to lower IOP with circumferential treatment.5
Even with excellent IOP control after trabeculotomy, the eye care professional must be wary of strabismus, amblyopia, cataract, and corneal disease. Thus, a multifaceted approach is necessary to achieve the triumph of good vision in these cases.
When angle surgery is unsuccessful, most glaucoma subspecialists turn to drainage implants, including valved and nonvalved devices. The major problem with tubes in children revolves around their revision. Strabismus may be a problem after the implantation of a drainage device. If an implant fails to control IOP, a second drainage device may be necessary, or improved types of cyclodestruction such as transscleral diode or endocyclophotocoagulation can be useful.
Knowledge gained through managing angle surgery in childhood glaucoma has spilled over into the treatment of adult glaucomas.7 Several types of adult glaucomas respond well to circumferential trabeculotomy, which allows good IOP control without a bleb.8,9 Increasing aqueous outflow through resident collector channels in all age groups remains an exciting avenue of glaucoma management, and it represents a significant advance in eye care.
Ronald L. Fellman, MD, is a glaucoma specialist at Glaucoma Associates of Texas in Dallas and clinical associate professor emeritus in the Department of Ophthalmology at UT Southwestern Medical Center in Dallas. He is a consultant to Endo Optiks. Dr. Fellman may be reached at (214) 360-0000; email@example.com.
- Fellman RL, Grover DS, Spaeth GL. Gonioscopy. In: Tasman W, Jaeger EA, eds. Duane's Clinical Ophthalmology. Philadelphia, PA: Lippincott Williams & Wilkins; 2012:1-23.
- Hollander DA, Sarfarazi M, Stoilov I, et al. Genotype and phenotype correlations in congenital glaucoma: CYP1B1 mutations, goniodysgenesis, and clinical characteristics. Am J Ophthalmol. 2006;142:993-1004.
- Beck AD, Lynch MG. 360 degree trabeculotomy for primary congenital glaucoma. Arch Ophthalmol. 1995;113(9):1200-1202.
- Sarkisian, SR Jr. An illuminated microcatheter for 360 degree trabeculotomy in congenital glaucoma: a retrospective case series. J AAPOS. 2010;14(5):412-416.
- Girkin CA, Rhodes L, McGwin G, et al. Goniotomy versus circumferential trabeculotomy with an illuminated microcatheter in congenital glaucoma. J AAPOS. 2012;16:424-427.
- Fellman RL. Trabeculotomy. In. Spaeth G, ed. Ophthalmic Surgery: Principles and Practice. 3rd ed. Philadelphia: Saunders; 2003:355-368.
- Godfrey DG, Fellman RL, Neelakantan A. Canal surgery in adult glaucomas. Curr Opin Ophthalmol. 2009;20:116-121.
- Chin S, Nitta T, Shinmei Y, et al. Reduction of intraocular pressure using a modified 360-degree suture trabeculotomy technique in primary and secondary open-angle glaucoma: a pilot study. J Glaucoma. 2012;21:401-407.
- Fellman RL. Trabeculotomy surgery in adults. In: Shacknow PN, Samples JR, eds. The Glaucoma Book. New York: Springer; 2010:789-794.